The present invention disclosed herein relates to a method of removing an oxide from a substrate and a method of manufacturing a semiconductor device using the same.
In semiconductor industries, integrated circuits have been improved in performance by simply reducing a size of a device to achieve a high response speed and low power consumption or by increasing the number of transistor to be integrated to one circuit. However, as the device decreases in size, non-negligible phenomena have been observed, which had never been seen in a large-scaled transistor. Particularly, when gate oxide has a thickness of about 4 nm or less, electron tunneling that leads to gate leakage current may occur. As a result, a gate dielectric has to have a thick thickness, however, if the gate dielectric has a thick thickness, it may be difficult to maintain sufficient capacitance for operating the device. Thus, high-k materials having high polarizability that allow the integrated circuit to have sufficient capacitance even when the gate dielectric has a thick thickness are alternately actively being studied.
Due to the limitation in the reducing of the size of the device, alternative methods for operating the integrated circuit at a high rate are being required. One of the methods is using a channel alternate material such as germanium. In this case, since the germanium has electron and hall mobility higher than those of the existing silicon, the substrate may be improved in performance.
However, the germanium has a native oxide very unstable thermally, unlike silicon oxide (SiO2) very stable thermally, diffusion of the germanium to the oxide layer at a high temperature may not be prevented. Meanwhile, among germanium oxides, although GeO and GeO2 are thermally unstable, Ge2O and Ge2O3 are thermally stable. A wet cleaning method has been used so as to remove the oxides. However, the wet cleaning method may not prevent a native oxide having a thickness of about 1 nm to about 2 nm from being formed again when next gate oxide is deposited, and thus deadly defects may occur in the device.